(i) Field of the Invention
This invention relates to cyclone separators.
(ii) Prior Art
U.S. Pat. No. 4,237,006 (Colman et al) describes a cyclone separator having a separating chamber having first, second and third contiguous cylindrical portions arranged in that order, the first cylindrical portion being of greater diameter than the second cylindrical portion and the third cylindrical portion being of lesser diameter than the second cylindrical portion, the first cylindrical portion having an overflow outlet at the end thereof opposite to said second cylindrical portion and a plurality of tangentially directed feed inlets, the separator being adapted to separate liquids one from the other in a mixture when infed into said separating chamber via said feed inlets, one said liquid emerging from said overflow outlet and the other emerging from the end of said third cylindrical portion remote from said first cylindrical portion.
The above separator is intended specifically, but not exclusively, for separating oil from water, the oil in use emerging from the overflow outlet and the water from said third cylindrical portion.
The aforementioned cylindrical portions may not be truly cylindrical, in the sense that they do not need in all cases to present a side surface which is linear in cross-section and parallel to the axis thereof. For example, U.S. Pat. No. 4,237,006 describes arrangements wherein the first cylindrical portion has a frustoconical section adjacent the second cylindrical portion and which provides a taper between the largest diameter of the first cylindrical portion and the diameter of the second cylindrical portion where this meets the first cylindrical portion. Likewise, the aforementioned patent specification describes arrangements wherein a similar section of frustoconical form is provided to cause a tapering in the diameter of the second cylindrical portion from a largest diameter of the second cylindrical portion to the diameter of the third cylindrical portion. There is also described an arrangement wherein the second cylindrical portion exhibits a constant taper over its whole length.
A difficulty has been found in operating cyclone separators of the kind described in U.S. Pat. No. 4,237,006 in that proper and reliable separating action is not always achieved, and contamination of the heavier liquid component (that emerging from the aforementioned third cylindrical portion of the separator) with the lighter liquid component occurs.